There are various techniques that can be used to heat and maintain a reactor vessel containing liquid sulfur at an appropriate start-up and steady-state operating temperature. However, known techniques have drawbacks due to the corrosive nature of the reactor contents, as well as the extreme temperature range encountered during a production cycle (from start-up to steady-state production to shutdown), which can often span a temperature range of 500° C. or more. Therefore, it would be beneficial to have reactor vessels with improved heating systems for more efficient and long-term operation. Accordingly, it is to these ends that the present disclosure is directed.